Salts Having Alkoxytris(Fluoroalkyl)Borate Anions

ABSTRACT

The invention relates to salts having alkoxytris(fluoroalkyl)borate anions which on the one hand are used for the synthesis of ionic liquids, but on the other hand can be employed per se as ionic liquid, and to processes for the preparation thereof.

The invention relates to salts having alkoxytris(fluoroalkyl)borateanions, and to processes for the preparation thereof.

The salts according to the invention can on the one hand be used for thesynthesis of ionic liquids, on the other hand the salts can be employedper se as ionic liquid.

Ionic liquids or liquid salts are ionic species which consist of anorganic cation and a generally inorganic anion. They do not contain anyneutral molecules and usually have melting points below 373 K.

The area of ionic liquids is currently the subject of intensive researchsince the potential applications are multifarious. Review articles onionic liquids are, for example, R. Sheldon “Catalytic reactions in ionicliquids Chem. Commun., 2001, 2399-2407; M. J. Earle, K. R. Seddon “Ionicliquids. Green solvent for the future”, Pure Appl. Chem., 72 (2000),1391-1398; P. Wasserscheid, W. Keim “Ionische Flüssigkeiten—neueLösungen für die Übergangsmetalikatalyse” [Ionic Liquids—Novel Solutionsfor Transition-Metal Catalysis], Angew. Chem., 112 (2000), 3926-3945; T.Welton “Room temperature ionic liquids. Solvents for synthesis andcatalysis”, Chem. Rev., 92 (1999), 2071-2083 or R. Hagiwara, Ya. Ito“Room temperature ionic liquids of alkylimidazolium cations andfluoroanions”, J. Fluorine Chem., 105 (2000), 221-227.

The properties of ionic liquids, for example melting point, thermal andelectrochemical stability, viscosity, are strongly influenced by thenature of the anion. By contrast, the polarity and hydrophilicity orlipophilicity can be varied by a suitable choice of the cation/anionpair. As cations, ionic liquids contain, for example, alkylphosphonium,alkylammonium, sulfonium or heterocyclic cations, such as1,3-dialkylimidazolium or N-alkylpyridinium. Known anions are, forexample, [AlCl₄]⁻, [Al₂Cl₇]⁻, NO₃ ⁻, BF₄ ⁻, PF₆ ⁻, alkyl- andarylsulfonates, phosphates, imides, methides, carboxylates or also inertcarboranes.

E. Bernhardt et al, Z. Anorg. Allg. Chem. 2000, 626, 560, E. Bernhardtet al, Chem. Eur. J. 2001, 7, 4696 and E. Bernhardt et al, Z. Anorg.Allg. Chem. 2003, 629, 1229 disclose the novel chemically andelectrochemically stable borate anions [B(CN)₄]⁻, [F_(x)B(CN)_(4-x)]⁻,where x=1 to 3, and [B(CF₃)₄]⁻.

EP 1205480 A1 describes tetrakisfluoroalkylborate salts and the usethereof as conductive salts or ionic liquids.

The object of the present invention was to provide novel and thermallyand electrochemically and also hydrolysis-stable salt-like compoundswhich can be used as ionic liquids or for the synthesis of ionicliquids, and a process for the preparation thereof.

The object is achieved by the salts of the formula (1) according to theinvention.

The invention therefore relates to salts of the general formula (1)

M^(a+)[RO—B(R^(F))₃]_(a)   (1)

in which

M^(a+) denotes a mono- or divalent cation,

a denotes 1 or 2,

R denotes straight-chain or branched alkyl having 1 to 10 C atoms, arylor aryl-C₁-C₆-alkyl and

R^(F) in each case, independently of one another, denotes fluorinatedstraight-chain or branched alkyl having 1 to 20 C atoms, fluorinatedstraight-chain or branched C₁-C₆-alkylaryl or fluorinatedaryl-C₁-C₆-alkyl.

An alkyl group having 1 to 10 C atoms is taken to mean, for example,methyl, ethyl, isopropyl, propyl, butyl, sec-butyl or tert-butyl,furthermore also pentyl, 1-, 2- or 3-methylbutyl, 1,1-, 1,2- or2,2-dimethylpropyl, 1-ethylpropyl, hexyl, heptyl, octyl, nonyl or decyl.The alkyl groups may also be partially or fully substituted by halogens,in particular —F and/or —Cl. Fluorinated alkyl groups aredifluoromethyl, trifluoromethyl, pentafluoroethyl, pentafluoropropyl,heptafluoropropyl, heptafluorobutyl or nonafluorobutyl.

Aryl denotes phenyl or naphthyl, preferably phenyl.

Aryl-C₁-C₆-alkyl denotes, for example, benzyl, phenylethyl,phenylpropyl, phenylbutyl, phenylpentyl or phenylhexyl. Fluorinatedaryl-C₁-C₆-alkyl denotes, for example, pentafluorophenyldifluoromethylor pentafluorophenyltetrafluoroethyl.

Fluorinated straight-chain or branched C₁-C₆-alkylaryl means that thefluorinated aryl group is substituted by a fluorinated C₁-C₆-alkylgroup, for example —C₆F₄CF₃, —C₆F₄C₂F₅, —CrF₄C₃F₇, —C₆F₄C₄F₉, —C₆F₄C₅F₁₁or —C₆F₄C₆F₁₃.

R is preferably straight-chain or branched alkyl having 1 to 10 C atoms,particularly preferably straight-chain or branched alkyl having 1 to 6 Catoms. R is very particularly preferably methyl, ethyl, propyl ori-propyl. R is especially very particularly preferably methyl.

R^(F) is preferably perfluorinated straight-chain or branched alkylhaving 1 to 20 C atoms, particularly preferably perfluorinatedstraight-chain or branched alkyl having 1 to 6 C atoms. RF is veryparticularly preferably trifluoromethyl.

In accordance with the invention, preference is given to a group ofcompounds of the formula I in which the cation M^(a+) is an alkali metalcation, preferably a lithium, sodium or potassium cation.

This group of compounds is particularly suitable for the synthesis ofionic liquids having the anion according to the invention by metathesiswith a salt MX, consisting of an organic cation, as defined below, andthe counterion XF⁻, Cl⁻, Br⁻, I⁻, [HF₂]⁻, [CN]⁻, [SCN]⁻, [CH₃COO]⁻,[CH₃SO₃]⁻, [CF₃COO]⁻, [CF₃SO₃]⁻, [CH₃OSO₃]⁻, [SiF₆]²⁻, [BF₄]⁻, [SO₄]²⁻,[NO₃]⁻, [C₂H₅OSO₃]⁻, [(C₂F₅)₂P(O)O]⁻, [C₂F₅P(O)O₂]²⁻, tosylates,malonates, substituted malonates or [CO₃]²⁻, where electroneutralityshould be taken into consideration in the formula of the salt MX. Theanion is preferably F⁻, Cl⁻, Br⁻, I⁻, [HF₂]⁻, [CH₃SO₃]⁻, [CH₃OSO₃]⁻,[CF₃COO]⁻, [CF₃SO₃]⁻, [(C₂F₅)₂P(O)O]⁻ or [CO₃]²⁻, particularlypreferably Cl⁻, Br⁻, [CH₃OSO₃]⁻, [CF₃SO₃]⁻ or [(C₂F₅)₂P(O)O]⁻.

The lithium compounds in this group are particularly suitable asconductive salts in electrolytes, primary batteries, secondarybatteries, capacitors, supercapacitors or electrochemical cells,optionally also in combination with further conductive salts and/oradditives, as constituent of a polymer electrolyte or phase-transfermedium.

In accordance with the invention, preference is given to a group ofcompounds of the formula I in which the cation M^(a+) is a silver,magnesium, copper(I), copper(II), zinc(II) or calcium(II) cation. Thecopper(II), zinc(II) or calcium(II) cations are preferably in solvatedform.

This group of compounds is likewise suitable for the synthesis of ionicliquids having the anion according to the invention by metathesis with asalt MX, as described above for the compounds of the formula I havingalkali metal cations.

This group of compounds is particularly suitable for metal deposition oras phase-ransfer medium.

In accordance with the invention, preference is given to a group ofcompounds of the formula I in which the cation MSa is an organic cation.

The organic cation here can be selected from the group [NR¹R²R³R⁴]⁺,[PR¹R²R³R⁴]⁺, [P(NR¹R²)₂(NR³R⁴)₂]⁺, [C(NR¹R²)(NR³R⁴)(NR⁵R⁶)]⁺,[(R¹R²N)—C(═OR⁷)(NR³R⁴)]⁺ and [(R¹R²N)—C(═SR⁷)(NR³R⁴)]⁺, where

R¹ to R⁷ each, independently of one another, denote hydrogen orstraight-chain or branched alkyl having 1 to 20 C atoms,

straight-chain or branched alkenyl having 2-20 C atoms and one or moredouble bonds,

straight-chain or branched alkynyl having 2-20 C atoms and one or moretriple bonds,

saturated, partially or fully unsaturated cycloalkyl having 3-7 C atoms,which may be substituted by alkyl groups having 1-6 C atoms, where oneor more of the substituents R¹ to R⁷ may be partially or fullysubstituted by halogens, in particular —F and/or —Cl, or partially by—CN or —NO₂ and where, in the substituents R¹ to R⁶, one or twonon-adacent carbon atoms which are not in the α-position may be replacedby atoms and/or atom groups selected from the group —O—, —C(O)—,—C(O)O—, —S—, —S(O)—, —SO₂—, —SO₂O—, —N═, —N═N—, —NH—, —NR′—, —PR′—,—P(O)R′—, —P(O)R′—O—, —O—P(O)R′—O—, —P(O)(NR′₂)—NR′— and —PR′₂═N—, whereR′=non-, partially or perfluorinated C₁- to C₆-alkyl, C₃- toC₇-cycloalkyl, unsubstituted or substituted phenyl or an unsubstitutedor substituted heterocycle.

A straight-chain or branched alkenyl having 2 to 20 C atoms, where aplurality of double bonds may also be present, is, for example, allyl,2- or 3-butenyl, isobutenyl, sec-butenyl, furthermore 4-pentenyl,isopentenyl, hexenyl, heptenyl, octenyl, —C₉H₁₇, —C₁₀H₁₉ to —C₂₀H₃₉,preferably allyl, 2- or 3-butenyl, isobutenyl, sec-butenyl, preferenceis furthermore given to 4-pentenyl, isopentenyl or hexenyl.

A straight-chain or branched alkynyl having 2 to 20 C atoms, where aplurality of triple bonds may also be present, is, for example, ethynyl,1- or 2-propynyl, 2- or 3-butynyl, furthermore 4-pentynyl, 3-pentynyl,hexynyl, heptynyl, octynyl, —C₉H₁₅, —C₁₀H₁₇ to —C₂₀H₃₇, preferablyethynyl, 1- or 2-propynyl, 2- or 3-butynyl, 4-pentynyl, 3-pentynyl orhexynyl.

Unsubstituted saturated or partially or fully unsaturated cycloalkylgroups having 3-7 C atoms are therefore cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl, cyclopentenyl,cyclopenta-1,3-dienyl, cyclohexenyl, cyclohexa-1,3-dienyl,cyclohexa-1,4-dienyl, phenyl, cycloheptenyl, cyclohepta-1,3-dienyl,cyclohepta-1,4-dienyl or cyclohepta-1,5-dienyl, each of which may besubstituted by C₁- to C₆-alkyl groups, where the cycloalkyl group or thecycloalkyl group which is substituted by C₁- to C₆-alkyl groups may inturn also be substituted by halogen atoms, such as F, Cl, Br or I, inparticular F or Cl, CN or NO₂.

The substituents R¹ to R⁷ may be partially or fully substituted byhalogen atoms, in particular by F and/or Cl, or partially by CN or NO₂.

Furthermore, the substituents R¹ to R⁶ may contain one or twonon-adjacent heteroatoms or atom groups selected from the group —O—,—C(O)—, —C(O)O—, —S—, —S(O)—, —SO₂—, —SO₂O—, —N—, —N═N—, —NH—, —NR′—,—PR′—, —P(O)R′—, —P(O)R′—O—, —O—P(O)R′—O—, —P(O)(NR′₂)—NR′— and—PR′₂═N—, where R′ can be a non-, partially or perfluorinated C₁- toC₆-alkyl, C₃- to C₇-cycloalkyl, unsubstituted or substituted phenyl oran unsubstituted or substituted heterocycle, which are not in thea-position to a nitrogen atom or phosphorus atom.

In R′, C₃- to C₇-cycloalkyl is, for example, cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl or cycloheptyl.

In R′, substituted phenyl denotes phenyl which is substituted by C₁- toC₆-alkyl, C₁- to C₆-alkenyl, NO₂, F, Cl, Br, I, OH, C₁-C₆-alkoxy, CN,SCN, SCF₃, SO₂CF₃, C(O)O—C₁-C₆-alkyl, NH₂, C₁-C₆-alkylamino orC₁-C₆-dialkylamino, COOH, C(O)NR″₂, SO₂OR″, SO₂X′, SO₂NR−₂, SO₃H orNHC(O)R″, where X′ denotes F, Cl or Br and R″ denotes a non-, partiallyor perrfuorinated C₁- to C₆-alkyl or C₃- to C₇-cycloalkyl, as definedfor R′, for example o-, m- or p-methylphenyl, o-, m- or p-ethylphenyl,o-, m- or p-propylphenylt, o-, m- or p-isopropylphenyl, o-, m- orp-tert-butylphenyl, o-, m- or p-aminophenyl, o-, m- orp-(N,N-dimethylamino)phenyl, o-, m- or p-nitrophenyl, o-, m- orp-hydroxyphenyl, o-, m- or p-methoxyphenyl, o-, m- or p-ethoxyphenyl,o-, m-, p-(trifluoromethyl)phenyl, o-, m-, p-(trifluoromethoxy)phenyl,o-, m-, p-(trifluoromethylsulfonyl)phenyl, o-, m- or p-fluorophenyl, o-,m- or p-chlorophenyl, o-, m- or p-bromophenyl, o-, m- or p-iodophenyl,furthermore preferably 2,3-, 2,4-, 2,5-, 2,6-, 3,4- or3,5-dimethylphenyl, 2,3-, 2,4-, 2,5-, 2,6-, 3,4- or 3,5-dihydroxyphenyl,2,3-, 2,4-, 2,5-, 2,6-, 3,4- or 3,5-difluorophenyl, 2,3-, 2,4-, 2,5-,2,6-, 3,4- or 3,5-dichlorophenyl, 2,3-, 2,4-, 2,5-, 2,6-, 3,4- or3,5-dibromophenyl, 2,3-, 2,4-, 2,5-, 2,6-, 3,4- or 3,5-dimethoxyphenyl,5-fluoro-2-methylphenyl, 3,4,5-trimethoxyphenyl or2,4,5-trimethylphenyl.

In R′, heterocycle is taken to mean a saturated or unsaturated mono- orbicyclic heterocyclic radical having 5 to 13 ring members, in which 1, 2or 3 N and/or 1 or 2 S or O atoms may be present and the heterocyclicradical may be mono- or polysubstituted by C₁- to C₆-alkyl, C₁- toC₆-alkenyl, NO₂, F, Cl, Br, I, OH, C₁-C₆-alkoxy, CN, SON, SCF₃, SO₂CF₃,C(O)O—C₁-C₆-alkyl, NH₂, C₁-C₆-alkylamino or C₁-C₆-dialkylamino, COOH,C(O)NR″₂, SO₂OR″, SO₂X′, SO₂NR″₂, SO₃H or NHC(O)R″, where X′ and R″ havean above-mentioned meaning.

The heterocyclic radical is preferably substituted or unsubstituted 2-or 3-furyl, 2- or 3-thienyl, 1-, 2- or 3-pyrrolyl, 1-, 2-, 4- or5-imidazolyl, 3-, 4- or 5-pyrazolyl, 2-, 4- or 5-oxazolyl, 3-, 4- or5-isoxazolyl, 2-, 4- or 5-thiazolyl, 3-, 4- or 5-isothiazolyl, 2-, 3- or4-pyridyl, 2-, 4-, 5- or 6-pyrimidinyl, furthermore preferably1,2,3-triazol-1-, -4- or -5-yl, 1,2,4-triazol-1-, -4- or -5-yl, 1- or5-tetrazolyl, 1,2,3-oxadiazol-4- or -5-yl, 1,2,4-oxadiazol-3- or -5-yl,1,3,4-thiadiazol-2- or -5-yl, 1,2,4-thiadiazol-3- or -5-yl,1,2,3-thiadiazol-4- or -5-yl, 2-, 3-, 4-, 5- or 6-2H-thiopyranyt, 2-, 3-or 4-4H-thiopyranyl, 3- or 4-pyridazinyl, pyrazinyl, 2-, 3-, 4-, 5-, 6-or 7-benzofuryl, 2-, 3-, 4-, 5-, 6- or 7-benzothienyl, 1-, 2-, 3-, 4-,5-, 6- or 7-1H-indolyl, 1-, 2-, 4- or 5-benzimidazolyl, 1-, 3-, 4-, 5-,6- or 7-benzopyrazolyl, 2-, 4-, 5-, 6- or 7-benzoxazolyl, 3-, 4-, 5-, 6-or 7-benzisoxazolyl, 2-, 4-, 5-, 6- or 7-benzothiazolyl, 2-, 4-, 5-, 6-or 7-benzisothiazolyl, 4-, 5-, 6- or 7-benz-2,1,3-oxadiazolyl, 1-, 2-,3-, 4-, 5-, 6-, 7- or 8-quinolinyl, 1-, 3-, 4-, 5-, 6-, 7- or8-isoquinolinyl, 1-, 2-, 3-, 4- or 9-carbazolyl, 1-, 2-, 3-, 4-, 5-, 6-,7-, 8- or 9-acridinyl, 3-, 4-, 5-, 6-, 7- or 8-cinnolinyl, 2-, 4-, 5-,6-, 7- or 8-quinazolinyl or 1-, 2- or 3-pyrrolidinyl.

Without restricting generality, examples of substituents R¹ to R⁶ oralso below of substituents R¹′ to R⁴′ are:

-   —CH₃, —C₂H₅, —C₃H₇, —CH(CH₃)₂, —C₄H₉, —C(CH₃)₃, —C₅H₁₁, —C₆H₁₃,    —C₇H₁₅, —C₈H₁₇, —C₉H₁₉, —C₁₀H₂₁, —C₁₂H₂₅, —C₂₀H₄₁, —CH₂OCH₃,    —C₂H₄OCH(CH₃)₂, —C₂H₄SC₂H₅, —C₂H₄SCH(CH₃)₂, —CH₂SO₂CH₃,    —CH₂N(H)C₂H₅, —C₂H₄N(H)C₂H₅, —CH₂N(CH₃)CH₃, —CN, —C₂H₄N(CH₃)CH₃,    —CF₃, —C₂F₅, —C₃F₇, —C₄F₉, —C(CF₃)₃, —CF₂SO₂CF₃, —C₂F₄N(C₂F₅)C₂F₅,    —CHF₂, —CH₂CF₃, —C₂F₂H₃, —C₃FH₆, —CH₂C₃F₇, —C(CFH₂)₃, —CH₂C(O)OH,    —CH₂C₆H₅, —CH₂C(O)CH₃, —CH₂C(O)C₂H₅, —CH₂C(O)OCH₃, CH₂C(O)OC₂H₅,    —C(O)CH₃, —C(O)C₆H₅, —C(O)OCH₃, —C(O)OC₂H₅,

Up to four substituents of the guanidinium cation[C(NR¹R²)(NR³R⁴)—(NR⁵R⁶)]⁺ may also be connected in pairs in such a waythat mono-, bi- or polycyclic cations are formed.

Without restricting generality, examples of such guanidinium cationsare:

where the substituents R¹ to R³ and R⁶ may have an above-mentioned orparticularly preferred meaning.

The carbocycles or heterocycles of the above-mentioned guanidiniumcations may optionally also be substituted by C₁- to C₆-alkyl, C₁- toC₆-alkenyl, NO₂, F, Cl, Br, I, OH, C₁-C₆-alkoxy, CN, SCN, SCF₃, SO₂CF₃,C(O)O—C₁-C₆-alkyl, NH₂, C₁-C₆-alkylamino or C₁-C₆-dialkylamino, COOH,C(O)NR″₂, SO₂OR″, SO₂NR″₂, SO₂X′, SO₃H or NHC(O)R″, where X′ and R″ havean above-mentioned meaning, substituted or unsubstituted phenyl or anunsubstituted or substituted heterocycle,

Up to four substituents of the uronium cation [(R¹R²N)—C(═OR⁷)(NR³R⁴)]⁺or of the thiouronium cation [(R¹R²N)—O(═SR⁷)(NR³R⁴)]⁺ may also beconnected in pairs in such a way that mono-, bi- or polycyclic cationsare formed. Without restricting generality, examples of such cations areindicated below, where X═O or S:

where the substituents R¹, R³ and R⁷ may have an above-mentioned orparticularly preferred meaning.

The carbocycles or heterocycles of the above-mentioned cations mayoptionally also be substituted by C₁- to C₆-alkyl, C₁- to C₆-alkenyl,NO₂, F, Cl, Br, I, OH, C₁-C₆-alkoxy, CN, SCN, SOF₃, SO₂CF₃,C(O)O—C₁-C₆-alkyl, NH₂, C₁-C₆alkylamino or C₁-C₅-dialkylamino, COOH,C(O)NR″₂, SO₂OR″, SO₂NR″₂, SO₂X′, SO₃H or NHC(O)R″ or substituted orunsubstituted phenyl or an unsubstituted or substituted heterocycle,where X′ and R″ have an above-mentioned meaning.

The organic cation is particularly preferably selected from the group ofthe ammonium, phosphonium and guanidinium salts.

The substituents R¹ to R⁷ are each, independently of one another,preferably a straight-chain or branched alkyl group having 1 to 10 Catoms R¹ to R⁷ are particularly preferably methyl, ethyl, propyl,i-propyl or butyl.

The substituents R¹ to R⁴ in the formulae [NR¹R²R³R⁴]⁺ or [PR¹R²R³R⁴]⁺are particularly preferably identical.

As a consequence of the synthesis, preference is given to a group ofsalts in which one substituent R¹, R², R³, R⁴, R⁵ or R⁶ or, in the caseof uronium and thiouronium, R⁷ is identical to the substituent R of theanion.

The organic cation can furthermore be selected from the group of theheterocyclic cations. Heterocyclic cations are, for example,

where the substituents

R¹′ to R⁴′ each, independently of one another, denote hydrogen,

straight-chain or branched alkyl having 1-20 C atoms,

straight-chain or branched alkenyl having 2-20 C atoms and one or moredouble bonds,

straight-chain or branched alkynyl having 2-20 C atoms and one or moretriple bonds,

saturated, partially or fully unsaturated cycloalkyl having 3-7 C atoms,which may be substituted by alkyl groups having 1-6 C atoms, saturated,partially or fully unsaturated heteroaryl, heteroaryl-C₁-C₆-alkyl oraryl-C₁-C₆-alkyl,

where one or more substituents R¹′ to R⁴′ may be partially or fullysubstituted by halogens, in particular —F and/or —Cl, or partially by—CN or —NO₂, and where, in the substituents R¹′ to R⁴′, one or twonon-adjacent carbon atoms which are not bonded to the heteroatom in theα-position may be replaced by atoms and/or atom groups selected from thegroup —O—, —C(O)—, —C(O)O—, —S—, —S(O)—, —SO₂—, —SO₂O—, —N═, —N═N—,—NH—, —NR′—, —PR′—, —P(O)R′—, —P(O)R′—O—, —O—P(O)R′—O—, —P(O)(NR′₂)—NR′—and —PR′₂═N—, where R′=non-, partially or perfluorinated C₁- toC₆-alkyl, C₃- to C₇-cycloalkyl, unsubstituted or substituted phenyl oran unsubstituted or substituted heterocycle.

The substituents R¹′ to R⁴′ are particularly preferably a straight-chainor branched alkyl group having 1 to 20 C atoms, very particularlypreferably having 1 to 12 C atoms.

As a consequence of the synthesis, preference is given to a group ofcompounds in which one substituent R¹′ or R⁴′ is identical to thesubstituent R of the anion component. Preference is furthermore given tosalts of the formula (1) having heterocyclic cations, as defined above,in which the substituents R¹′ and R⁴′ are different.

From the group of heterocyclic organic cations, the cations areparticularly preferably selected from substituted imidazolium,substituted pyridinium, substituted pyrrolidinium, substitutedpiperidinium and substituted morpholinium, as defined above.

The salts of the formula (1) according to the invention having organiccations, as described above, can be used as ionic liquids. Ionic liquidscan be employed, for example, as solvents for many synthetic orcatalytic reactions, for example Friedel-Crafts acylation andalkylation, Diels-Aider cyclo-additions, hydrogenation and oxidationreactions, Michael-type reactions or Heck reactions, as non-aqueouselectrolytes, which are optionally employed in combination with otherconductive salts known to the person skilled in the art, additives andsolvents.

In addition, the ionic liquids according to the invention can be used asnon-aqueous polar substances in suitable reactions, as phase-transfercatalyst, as surfactant (surface-active agent) or as medium for theheterogenisation of homogeneous catalysts.

They are furthermore suitable as desiccants and as separation media forgases.

The present invention secondly relates to a process for the preparationof the salts of the formula (1) according to the invention,characterised in that a dialkyloxonium tris(fluoroalkyl)borate of theformula (2)

(R)₂O—B(R^(F))₃   (2)

where R and R^(F) have a meaning indicated for the compounds of theformula (1), is reacted with an inorganic salt containing the metalcation M^(a+), as described above, or with an alkylatable organiccompound, for example an amine, phosphine, guanidine, urea, thiourea ora heterocycle, corresponding to the cations, as described above.

Suitable inorganic salts for the preparation of the compounds of theformula (1) in which M^(a+) is an alkali metal cation or a cation fromthe group silver, magnesium, copper, zinc and calcium are, for example,Na₂CO₃, K₂CO₃, KOH, NaOH, Ag₂O, Ag₂CO₃, MgCO₃, KCl, CuO, ZnCO₃ orCa(CO₂CH₃)₂.

The reaction is preferably carried out in an organic solvent, forexample dichloromethane, a dialkyl ether, for example diethyl ether,ethyl acetate, water or an alcohols for example methanol or ethanol, ata temperature between 0° C. and 100° C., preferably between 10° and 80°C., particularly preferably at room temperature.

Suitable alkylatable organic starting materials for the synthesis ofcompounds of the formula (1) having organic cations are [NR¹R²R³],[PR¹R²R³], [P(NR¹R²)₂(NR³R⁴)], [C(NR¹R²)(═NR⁴)(NR⁵R⁶)],[(R¹R²N)—C(═O)(NR³R⁴)] or [(R¹R²N)—C(═S)(NR³R⁴)] and, for example, theheterocyclic compounds

where the substituents

R¹to R⁶ and R¹′ to R⁴′ are as defined above for the cations.

The reaction is preferably carried out under inert-gas conditions in anorganic solvent, for example dichloromethane, a dialkyl ether, forexample diethyl ether, ethyl acetate, nitromethane or acetonitrile, at atemperature between 0° C. and 100° C., preferably between 10° and 80°C., particularly preferably at room temperature.

This alkylation process inevitably gives compounds of the formula (1)having an organic cation, where one substituent, depending on thestarting material, for example R⁴ of the phosphonium or ammoniumcations, R⁷ of the uronium or thiouronium cations, or R¹′ or R⁴′ of theheterocyclic cations, is identical to the substituent R of the anioncomponent.

The dialkyloxonium tris(fluoroalkyl)borates of the formula (2)

(R)₂O—B(R^(F))₃   (2),

where R and R^(F) have a preferred or particularly preferred meaning, asindicated for the compounds of the formula (1), are novel.Dialkyloxonium tris(fluoroalkyl)borates are stable at room temperatureand are excellent alkylating agents. One application of these compoundsis in the synthesis of the compounds of the formula (1). However, theycan also be employed as general alkylating agents in other organicsyntheses.

The invention therefore also relates to compounds of the formula (2)

(R)₂O—B(R^(F))₃   (2),

in which

R denotes straight-chain or branched alkyl having 1 to 10 C atoms, arylor aryl-C₁-C₆-alkyl and

R^(F) in each case, independently of one another, denotes fluorinatedstraight-chain or branched alkyl having 1 to 20 C atoms, fluorinatedstraight-chain or branched C₁-C₆-alkylaryl or fluorinatedaryl-C₁-C₆-alkyl.

In compounds of the formula (2), R is preferably a straight-chain orbranched alkyl having 1 to 6 C atoms; R^(F) is preferably perfluorinatedalkyl having 1 to 6 C atoms. The substituents R^(F) are preferablyidentical.

Dialkyloxonium tris(fluoroalkyl)borates of the formula (2) are obtainedby reaction of a tris(fluoroalkyl)boron carbonyl of the formula (3)

(R^(F))₃BCO   (3),

where R^(F) in each case, independently of one another, has a meaningindicated for formula (1),

with a dialkyl ether of the formula (4)

(R)₂O   (4),

where R in each case, independently of one another, has a meaningindicated for formula (1).

Carbonyltris(trifluoromethyl)borane and a process for the preparationthereof is known from J. Am. Chem. Soc, 2002, 51, 15385 or Angew. Chem.2002, 114, 823. The other tris(fluoroalkyl)boron carbonyls of theformula (3) can be prepared analogously tocarbonyltris(trifluoromethyl)borane.

The dialkyl ether is preferably condensed into the boron carbonyl attemperatures between −200° and 25° C. or added to the boron carbonyl atroom temperature in a suitable solvent. The reaction mixture is thenwarmed to temperatures between 10° and 40°, particularly preferably toroom temperature, and stirred at this temperature for 10 to 14 hours.The desired product can be purified using conventional methods, as knownto the person skilled in the art. The purification is preferably carriedout by recrystallisation.

In accordance with the invention, the reagents in the alkylation can bereacted in a mixing ratio of up to a five-fold excess of one of thereactants, in particular the alkylating agent. However, the reactantsare preferably employed in equimolar amount.

By-products which form are, for example, the products[(R)₃O]⁺[(R^(F))₃BOR]⁻, [(R)₃O]⁺[(R^(F))₃BC(O)OR⁻ and/or(R^(F))₃BC(OR)₂, where the substituents R and R^(F) have a meaningindicated for formula (1).

These by-products are likewise strong alkylating agents.

The invention furthermore relates to a process for the preparation ofcompounds of the formula (1) in which M^(a+) is an organic cationwithout the restriction that a substituent of the organic cation isidentical to the substituent R of the anion component, characterised inthat

a compound of the formula (1)

M^(a+)[RO—B(R^(F))₃]_(a)   (1),

in which

M^(a+) denotes an alkali metal cation, a silver, magnesium, copper, zincor calcium cation, optionally in solvated form,

R denotes straight-chain or branched alkyl having 1 to 10 C atoms, arylor aryl-Cl-C₆-alkyl and

R^(F) in each case, independently of one another, denotes fluorinatedstraight-chain or branched alkyl having 1 to 20 C atoms, fluorinatedstraight-chain or branched C₁-C₆-alkylaryl or fluorinatedaryl-C₁-C₆-alkyl,

is reacted with a compound of the formula (5)

MX   (5),

in which

M is an organic cation, as defined above, and the anion X denotes F⁻,Cl⁻, Br⁻, I⁻, [HF₂]⁻, [CN]⁻, [SCN]⁻, [CH₃COO]⁻, [CH₃SO₃]⁻, [CF₃COO]⁻,[CF₃SO₃]⁻, [CH₃OSO₃]⁻,[SiF₆]²⁻, [BF₄]⁻, [SO₄]²⁻, [NO₃]⁻, [C₂H₅OSO₃]⁻,[(C₂F₅)₂P(O)O]⁻, [C₂F₅P(O)O₂]²⁻, tosylates, malonates, substitutedmalonates or [CO₃]²⁻, where electroneutrality should be taken intoconsideration in the formula of the salt MX.

The anion in the formula (5) is preferably F—, Cl—, Br—, I—, [HF₂]—,[CH₃SO₃]—, [CH₃OSO₃]⁻, [CF₃COO]⁻, [CF₃SO₃]⁻, [(C₂F₅)₂P(O)O]⁻ or [CO₃]²⁻,particularly preferably Cl⁻, Br⁻, [CH₃OSO₃]⁻, [CF₃SO₃] or[(C₂F₅)₂P(O)O]⁻.

The reaction is advantageously carried out in water, where temperaturesof 10°-100° C., preferably 15°-60° C., particularly preferably roomtemperature, are suitable.

However, the reaction can alternatively also be carried out in organicsolvents at temperatures between 10° and 100° C. Suitable solvents hereare benzene, acetonitrile, dioxane, dichloromethane, dimethoxyethane oran alcohol, for example methanol or ethanol.

The complete disclosure content of all applications, patents andpublications mentioned above and below is incorporated into thisapplication by way of reference.

Even without further comments, it is assumed that a person skilled inthe art will be able to utilise the above description in the broadestscope. The preferred embodiments and examples should therefore merely beregarded as descriptive disclosure which is absolutely not limiting inany way.

The NMR spectra were measured on solutions in deuterated solvents at 20°C. in a Bruker Avance 300 spectrometer with a 5 mm ¹H/BB broad-band headwith deuterium lock, unless indicated otherwise in the examples. Themeasurement frequencies of the various nuclei are: ¹H: 300.13 MHz, ¹¹B:96.92 MHz, ¹⁹F: 282.41 MHz and ³¹P: 121.49 MHz. The referencing methodis indicated separately for each spectrum or for each data set.

EXAMPLE 1 Synthesis of dimethyloxonium tris(trifluoromethyl)borate,(CH₃)₂OB(CF₃)₃

5 ml of dimethyl ether are condensed into 2.75 g (11.2 mmol) oftris(trifluoromethyl)boron carbonyl, (CF₃)₃BCO, at −196° C. The reactionmixture warms to room temperature, and stirring is continued overnight.The volatile constituents are distilled off in vacuo, giving 2.74 g of asolid which consists of 95.9% of (CF₃)₃BO(CH₃)₂. The crude product canbe freed from by-products by recrystallisation from adichloromethane/pentane mixture. The yield, based ontris(trifluoromethyl)boron carbonyl, is 89%.

Elemental analysis:

found: C, 22.41; H, 2,24;

calculated (C₅H₆BF₉O): C, 22.76; H, 2.29.

¹H-NMR (CD₂Cl₂, reference: TMS), δ [ppm]: 3.87 br.s.

¹¹B-NMR (Cl₂Cl₂, reference: BF₃.OEt₂ external), δ [ppm]: −5.1.

¹⁹F-NMR (CD₂Cl₂, reference: CFCl₃), δ [ppm]: −64.2 s.

¹³C-NMR of (CF₃)₃BO(CD₃)₂(CD₂Cl₂, reference: TMS), δ[ppm]: 72.0 (CD₃),128.1 (CF₃).

EXAMPLE 2 Synthesis of 1-butyl-3-methylimidazoliummethoxytris(trifluoromethyl)borate

0.211 g (1.70 mmol) of 1-n-butylimidazole is added with stirring underan inert-gas atmosphere to a solution of 0.448 g (1.70 mmol) ofdimethyloxonium tris(trifluoromethyl)borate in 3 ml of drydichloromethane. The reaction mixture is stirred overnight at roomtemperature, and the volatile products are subsequently distilled off invacuo, giving 0.66 g of liquid 1-butyl-3-methylimidazoliummethoxytris(trifluoromethyl)borate (m.p. <20° C.). The yield isapproximately quantitative.

Elemental analysis:

found: C, 36.89; H, 4.95; N, 7.49;

calculated (C₁₂H₁₈BF₉N₂O): C, 37.14; H, 4.68; N, 7.22.

¹H-NMR (CD₃CN, reference: TMS), δ [ppm]: 0.94 t (3H, CH₃), 1.26-1.40 m(2H, CH₂), 1.76-1.86 m (2H, CH₂), 3.33 br. s (3H, OCH₃), 3.82 s (3H,NCH₃), 4.12 t (2H, NCH₂), 7.29-7.41 m (2H), 8.43 s (1H).

¹¹B-NMR (OD₃CN, reference: BF₃.OEt₂ external), δ [ppm]: −9.5.

¹⁹F-NMR (CD₃CN, reference: CFCl₃), δ [ppm]: −65.1 s.

EXAMPLE 3 Synthesis of tri-n-butylmethylphosphoniummethoxytris(trifluoromethyl)borate

(n-C₄H₉)₃P+(CF₃)₃BO(CH₃)₂→(n-C₄H₉)₃ ⁺PCH₃[(CF₃)₃BOCH₃]⁻

0.276 g (1.36 mmol) of tri-n-butylphosphine in 3 ml of drydichloromethane is added with stirring under an inert-gas atmosphere toa solution of 0.360 g (1.36 mmol) of dimethyloxoniumtris(trifluoromethyl)borate in 3 ml of dry dichloromethane. The reactionmixture is stirred overnight at room temperature, and the volatileproducts are subsequently distilled off in vacuo, giving 0.643 g oftri-n-butylmethylphosphonium methoxytris(trifluoromethyl)borate (m.p.63° C.). The yield is approximately quantitative.

Elemental analysis:

found: C, 44.03; H, 7.08;

calculated (C₁₇H₃₃BF₉OP): C, 43.80; H, 7.13.

¹H-NMR (CD₃CN, reference: TMS), δ [ppm]: 0.95 t (9H, CH₃), 1.35-1.60 m(12H, 6CH₂), 1.68 d (3H, PCH₃), 1.98-2.13 m (6H, 3CH₂), 3.33 br. s(3H,OCH₃),²J_(P,H)=13.5 Hz.

¹¹B-NMR (CD₃CN, reference. BF₃.OEt₂ external), δ [ppm]: −9.5.

¹⁹F-NMR (CD₃CN, reference: CFCl₃), δ [ppm]: −65.1 s.

EXAMPLE 4 Synthesis of potassium methoxytris(trifluoromethyl)borate

(CF₃)₃BO₃(CH₃)₂+K₂CO₃+H₂O→K⁺(CF₃)₃BOCH₃]⁻+KHCO₃+CH₃OH

5 ml of a concentrated aqueous potassium carbonate solution are addedwith stirring at room temperature to a solution of 1.09 g (4.13 mmol) ofdimethyloxonium tris(trifluoromethyl)borate in 10 ml of dichloromethane.The reaction mixture is stirred for one hour and extracted three timeswith 150 ml, 100 ml and 50 ml of diethyl ether. The extract is driedover K₂CO₃. After the solid has been filtered off, the solvent isdistilled off in vacuo, giving 1.11 g of potassiummethoxytris(trifluoromethyl)borate, which corresponds to a yield of93.3%.

Elemental analysis:

found: C, 16.99; H, 1.05;

calculated (C₄H₃BF₉OK): C, 16.68; H, 1.05.

¹H-NMR (CD₃ON, reference: TMS), δ [ppm]: 3.33 br.s.

¹¹B-NMR (CD₃CN, reference. BF₃.OEt₂ external), δ [ppm]: −9.5.

¹⁹F-NMR (CD₃CN, reference: CFCl₃), δ [ppm]: −65.1 s.

¹³C-NMR of K[(CF₃)₃BOCD₃] (CD₃CN, reference: TMS), δ [ppm]: 51.3 (CD₃),133.6 (CF₃).

EXAMPLE 5 Synthesis of tetra-n-butylammoniummethoxytris(trifluoromethyl)borate

(n-C₄H₉)₄N⁺Cl⁻+K⁺[(CF₃)₃BOCH₃]⁻→(n-C₄H₉)₄N⁺[(CF₃)₃BOCH₃]⁻+KCl

0.215 g (0.78 mmol) of tetra-n-butylammonium chloride in 5 ml of wateris added to a solution of 0.245 g (0.85 mmol) of potassiummethoxytris(trifluoromethyl)borate in 5 ml of water, After two hours,the precipitate is filtered off and washed with 50 ml of water and driedin vacuo, giving 0.359 g of tetra-n-butylammoniummethoxytris(trifluoromethyi)borate (m.p. 134° C.), which corresponds toa yield of 94.2%.

Elemental analysis:

found: C, 48.92; H, 7.96; N, 2.85;

calculated (C₂₀H₃₉BF₉NO): C, 48.89; H, 8.00; N, 2,85.

¹H-NMR (CD₃CN, reference: TMS), δ [ppm]: 0.97 t (12H, 4CH₃), 1.28-1.42 m(8H, 4CH₂), 1.53-1.66 m (8H, 4CH₂), 3.02-3.12 m (8H, 4CH₂), 3.33 br. s(3H, OCH₃).

¹¹B-NMR (CD₃CN, reference: BF₃.OEt₂ external), δ [ppm]: −9.5.

¹⁹F-NMR (CD₃CN, reference: CFCl₃), δ [ppm]: −65.1 s.

1. Alkoxytris((per)fluoroalkyl)borate salts of the formula (1)M^(a+)[RO—B(R^(F))₃]_(a)   (1) in which M^(a+) denotes a mono- ordivalent cation, a denotes 1 or 2, R denotes straight-chain or branchedalkyl having 1 to 10 C atoms, aryl or aryl-C₁-C₆-alkyl and R^(F) in eachcase, independently of one another, denotes fluorinated straight-chainor branched alkyl having 1 to 20 C atoms, fluorinated straight-chain orbranched C₁-C₆-allcylaryl or fluorinated aryl-C₁-C₆-alkyl.
 2. Compoundsof the formula (1) according to claim 1, characterised in that M^(a+) isan alkali metal cation.
 3. Compounds of the formula (1) according toclaim 1, characterised in that Mar is a silver, magnesium, copper(I),copper(II), zinc(II) or calcium(II) cation.
 4. Compounds of the formula(1) according to claim 1, characterised in that M^(a+) is an organiccation.
 5. Compounds of the formula (1) according to claim 4,characterised in that the organic cation is selected from the group[NR¹R²R³R⁴)]⁺, [PR¹R²RR⁴]⁺, [P(NR¹R²)₂(NR³R⁴)₂]⁺,[C(NR¹R²)(NR³R⁴)R⁵R⁶)]⁺, [(R¹R²N)—C(═OR⁷)NR³R⁴)]⁺ and[(R¹R²N)—C(═SR⁷)(NR³R⁴)]⁺, in which R¹ to R⁷ each, independently of oneanother, denote hydrogen, straight-chain or branched alkyl having 1 to20 C atoms, straight-chain or branched alkenyl having 2-20 C atoms andone or more double bonds, straight-chain or branched alkynyl having 2-20C atoms and one or more triple bonds, saturated, partially or fullyunsaturated cycloallkyl having 37 C atoms, which may be substituted byalkyl groups having 1-6 C atoms, where one or more of the substituentsR¹ to R⁷ may be partially or fully substituted by halogens, inparticular —F and/or —Cl, or partially by —CN or —NO₂ and where, in thesubstituents RI to R⁶, one or two non-adjacent carbon atoms which arenot in the a-position may be replaced by atoms and/or atom groupsselected from the group —O—, —C(O)—, —C(O)O—, —S—, —S(O)—, —SO₂—,—SO₂O—, —N═, —N═N—, —NH—, —NR′—, —PR′—, —P(O)R′—, —P(O)R′—O—,—O—P(O)R′—O—, —P(O)(NR′₂)—NR′— and —PR′₂═N—, where R′=non-, partially orperfluorinated C₁- to C₆-alkyl, C₃- to C₇-cycloalkyl, unsubstituted orsubstituted phenyl or an unsubstituted or substituted heterocycle. 6.Compounds of the formula (1) according to claim 4, characterised in thatthe organic cation is a heterocyclic cation and is selected from thegroup

where the substituents R¹′ to R⁴′ each, independently of one another,denote hydrogen, straight-chain or branched alkyl having 1-20 C atoms,straight-chaini or branched alkenyl having 2-20 C atoms and one or moredouble bonds, straight-chain or branched allynyl having 2-20 C atoms andone or more triple bonds, saturated, partially or fully unsaturatedcycloalkyl having 3-7 C atoms, which may be substituted by alkyl groupshaving 1-6 C atoms, saturated, partially or fully unsaturatedheteroaryl, heteroaryl-C₁-C₆-alkyl or aryl-C₁-C₆-alkyl, where one ormore substituents R¹′ to R⁴′ may be partially or fully substituted byhalogens, in particular —F and/or —Cl, or partially by —CN or —NO₂, andwhere, in the substituents R¹′ to R⁴′, one or two non-adjacent carbonatoms which are not bonded to the heteroatom in the a-position may bereplaced by atoms and/or atom groups selected from the group —O—,—C(O)—, —C(O)O—, —S—, —S(O)—, —SO₂—, —SO₂O—, —N═, —N═N—, —NH—, —NR′—,—PR′—, —P(O)R′—, —P(O)R′—O—, —O—P(O)R′—O—, —P(O)(NR′₂)—NR′— and—PR′₂═N—, where R′=non-, partially or perfluorinated C₁- to C₆-alkyl,C₃- to C₇-cycloalkyl, unsubstituted or substituted phenyl or anunsubstituted or substituted heterocycle.
 7. Compounds according toclaim 1, characterised in that the substituent R in the anion is astraight-chain or branched alkyl group having 1 to 10 C atoms. 8.Compounds according to claim 1, characterised in that the substituentR^(F) in the anion is a perfluorinated straight-chain or branched alkylgroup having 1 to 20 C atoms.
 9. Process for the preparation of thesalts of the formula (1) according to claim 1, characterised in that adialkyloxonium tris(fluoroalkyl)borate of the formula (2)(R)₂O—B(R^(F))₃   (2) where R denotes straight-chain or branched alkylhaving 1 to 10 C atoms, aryl or aryl-C₁-C₆-alkyl and R^(F) in each case,independently of one another, denotes fluorinated straight-chain orbranched alkyl having 1 to 20 C atoms, fluorinated straight-chain orbranched C₁-C₆-alkylaryl or fluorinated aryl-C₁-C₆-alkyl, is reactedwith a) an inorganic salt containing a metal cation M^(a+) or b) with analkylatable organic compound.
 10. Compounds of the formula (2)(R)₂O—B(R^(F))₃   (2), in which R denotes straight-chain or branchedalkyl having 1 to 10 C atoms, aryl or aryl-Cl-C₆-alkyl and R^(F) in eachcase, independently of one another, denotes fluorinated straight-chainor branched alkyl having 1 to 20 C atoms, fluorinated straight-chain orbranched C₁-C₆-alkylaryl or fluorinated aryl-C₁-C₆-alkyl.
 11. Processfor the preparation of compounds of the formula (2), characterised inthat a tris(fluoroalkyl)boron carbonyl of the formula (3)(R^(F))₃BCO   (3), where R^(F) in each case, independently of oneanother, denotes fluorinated straight-chain or branched alkyl having 1to 20 C atoms, fluorinated straight-chain or branched C₁-C₆-alkylaryl orfluorinated aryl-C₁-C₆-alkyl, is reacted with a dialkyl ether of theformula (4)(R)₂O   (4), where R in each case, independently of one another, denotesstraight-chain or branched alkyl having 1 to 10 C atoms, aryl oraryl-C₁-C₆-alkyl.
 12. Use of the compounds of the formula (2) accordingto claim 10 as alkylating agents.
 13. Process for the preparation ofcompounds of the formula (1) according to claim 1, in which M^(a+) is anorganic cation without the restriction that a substituent of the organiccation is identical to the substituent R of the anion component,characterised in that a compound of the formula (1)M^(a+)[RO—B(R^(F))₃]_(a)   (1) in which M^(a+) denotes an alkali metalcation, a silver, magnesium, copper, zinc or calcium cation, a denotes 1or 2, R denotes straight-chain or branched alkyl having 1 to 10 C atoms,aryl or aryl-C₁-C₆-alkyl and R^(F) in each case, independently of oneanother, denotes fluorinated straight-chain or branched alkyl having 1to 20 C atoms, fluorinated straight-chain or branched C₁-C₆-alkylaryl orfluorinated aryl-C₁-C₆-alkyl, is reacted with a compound of the formula(5)MX   (5), in which M is an organic cation and the anion X denotes F⁻,Cl⁻, Br⁻, I⁻, [HF₂]⁻, [CN]⁻, [SCN]⁻, [CH₃COO]⁻, [Cl₃SO₃]⁻, [CF₃COO]⁻,[CF₃SO₃]⁻, [CH₃OSO₃]⁻, [SiF₆]^(2−, [BF) ₄]⁻, [SO₄]²⁻, [NO₃]⁻,[C₂H₅OSO₃]⁻, [(C₂F₅)₂P(O)O]⁻, [C₂F₅P(O)O₂]²⁻, tosylates, malonates,substituted malonates or [CO₃]²⁻.
 14. Use of a salt of the formula (1)according to claim 1 as ionic liquid.